A liquid crystal display device (LCD) is one example of flat display devices. The LCD displays data through physical optics characteristics. Since the LCD has a lower power consumption compared to other display devices, takes advantages of lightweight and thin properties, and can be manufactured in various sizes, it has been widely used in diverse fields.
The LCD includes a thin film transistor (TFT) array substrate, a color filter array substrate, and a liquid crystal. The color filter array substrate is disposed opposite to the TFT array substrate. The liquid crystal is interposed between the TFT array substrate and the color filter array substrate. The TFT array substrate includes a plurality of signal lines, and a pixel electrode connected to the TFT transistor. Additionally, the color filter array substrate includes a color filter layer for color displaying, and common electrodes.
The common electrode disposed on the color filter array substrate is electrically connected to a conductive part, which is disposed on the outside of the TFT array substrate. A common voltage supplied from an external circuit through the conductive part is supplied to the common electrode.
The common electrode is electrically connected to the conductive part through a silver dot medium. The silver dot is manufactured by coating silver in a paste state through a dispenser, drying the resulted silver dot during a predetermined time, and attaching the two substrates by pressure. At this point, in case the two substrates are attached when a silver paste coated on the TFT is not dried completely, the silver of a low density is formed. Therefore, the area contacting the common electrode is reduced and also an appropriate voltage can not be supplied.
To overcome this problem, there is provided an LCD having the conductive part formed through a conductive ball of a high density without the silver paste.
FIGS. 1A and 1B are views of an LCD using a related art conductive thread pattern. FIG. 1A is a plan view when a second substrate of I-I′ portion is removed from the LCD. FIG. 1B is a sectional view taken along line II-II′ of FIG. 1A.
Referring to FIGS. 1A and 1B, the related art LCD includes a first substrate 10 and a second substrate 20, which are defined by a display region A and a non-display region B. The first substrate 10 and the second substrate 20 are attached by a conductive thread pattern. A plurality of gate lines 40 and data lines 50 are crossing each other on the first substrate 10 corresponding to the display region A. Each crossing of the gate lines 40 and the data lines 50 includes at least one TFT, and a pixel electrode 60 electrically connected to the TFT.
A pad part is formed on the first substrate 100 corresponding to the non-display region B to connect to an external circuit. That is, at least two gate pad parts 70 are formed on one side of the first substrate 10. The gate pad part 70 includes a predetermined region to which the end of each gate line 40 is gathered. Moreover, at least two data pad parts 80 are formed on another side of the first substrate 10. The data pad part 60 includes a predetermined region to which the end of each data line is gathered. At this point, each of the pad parts is electrically connected to a printed circuit board (PCB) (not shown) through a tape automated bonding (TAB) 90.
On the other hand, a conductive part 85 is disposed between the data pad parts 80, and the conductive thread pattern 30 is disposed on the outside of the first substrate having the conductive part 85. The conductive pattern 30 includes sealant 30a and a conductive ball 30b. The conductive thread pattern 30 attaches the first substrate 10 to the second substrate 20. Additionally, the conductive thread pattern 30 connects the common electrode 22 in the second substrate 20, and the conductive part 85.
Thus, a common voltage is supplied from an external circuit to the conductive part 85. The common voltage applied to the conductive part 85 is supplied to the common electrode 22 through the conductive thread pattern 30.
The conductive part 85 includes a dummy pattern 85a and a dummy pattern contact part 85b. The dummy pattern 85a is simultaneously formed when source/drain electrodes 45a and 45b of the TFT, and the data line 50 are formed. The dummy pattern contact part 58b is simultaneously formed on the dummy pattern 85a when the pixel electrode is formed.
Since the dummy pattern 85a is simultaneously formed with the data line 50 and the source/drain electrodes 45a and 45b, there is no choice for selecting a conductive material of the dummy pattern 85a. That is, the dummy pattern 85a may be formed of a low resistance metal to minimize the loss of a common voltage supplied to the common electrode 22. However, when considering simplicity of processes, the dummy pattern 85a is formed of a conductive metal of the data line 50 and the source/drain electrodes 45a and 45b. 
Additionally, when the dummy pattern 85a, the data line 50, and data pad 80 are formed on an identical layer, there is limitation in designing the dummy pattern 85a. 